Gas turbine engine fan drive gear system damper

ABSTRACT

A gas turbine engine includes a fan section. A turbine section is coupled to the fan section via a geared architecture. The geared architecture includes a torque frame and a flex support spaced apart from one another at a location. A gear train is supported by the torque frame. A viscous damper is provided between the torque frame and the flex support at the location.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.13/557,515, filed Jul. 25, 2012 which is a continuation of U.S. patentapplication Ser. No. 13/432,699 filed Mar. 28, 2012.

BACKGROUND

This disclosure relates to a damper for a fan drive gear system for agas turbine engine.

Gear trains are used in gas turbine engines to provide a gear reductionbetween a turbine section and a fan, for example. The gear train issupported relative to a static structure. During operation, the geartrain generates vibrational inputs to the static structure and othercomponents, which may be undesirable. Additionally, the supportingstructure may transmit vibrational inputs to the fan drive gear systemthat may be coincident or undesirable to the fan drive gear system.Typically, a flex support having a bellow secures the gear train to thestatic structure to permit some relative movement between the gear trainand the static structure.

SUMMARY

In one exemplary embodiment, a a gas turbine engine includes first andsecond members spaced apart from one another at a location. A gear trainis supported by the first member. A viscous damper is provided betweenthe first member and the second member at the location.

In a further embodiment of any of the above, the first member is atorque frame. The second member is a flex support having a bellow. Theflex support is grounded to a static structure.

In a further embodiment of any of the above, the torque frame and flexsupport are secured to one another by fasteners in an area spacedradially inward from the location.

In a further embodiment of any of the above, multiple viscous dampersare arranged circumferentially between the torque frame and the flexsupport. The bellow is provided between the fasteners and the viscousdampers.

In a further embodiment of any of the above, the torque frame supports acarrier to which star gears are mounted. A sun gear is arrangedcentrally relative to and intermeshes with the star gears. A ring gearcircumscribes and intermeshes with the star gears.

In a further embodiment of any of the above, a fan is coupled to thering gear and a low speed spool is coupled to the sun gear.

In a further embodiment of any of the above, the first and secondmembers respectively include first and second apertures aligned with oneanother in an axial direction. The viscous damper extends between and isreceived in the first and second apertures.

In a further embodiment of any of the above, the viscous damper is atube that has opposing ends each supporting a seal. Each seal engages arespective first and second aperture.

In a further embodiment of any of the above, the tube provides a cavity.An orifice is provided in the tube in fluid communication with thecavity. The cavity provides a viscous damping chamber between the firstand second members.

In a further embodiment of any of the above, at least one of the geartrain and the second member is configured to produce a vibrationalinput. The orifice and viscous damping chamber is configured to damp thevibrational input.

In a further embodiment of any of the above, each end includes anannular groove that receives a respective seal and lateral sides areprovided on each end with the respective end's annular groove providedbetween the lateral sides. The lateral sides provide annular tapers thatextend radially inward away from the respective end's annular groove andare configured to permit articulation of the viscous damper relative tothe first and second members.

In a further embodiment of any of the above, the tube includes a neckarranged between ends and has a diameter that is smaller than a diameterof the ends.

In a further embodiment of any of the above, the viscous damper includesa tube having opposing ends each with an annular groove. A neck isarranged between ends and has a diameter that is smaller than a diameterof the ends. Lateral sides are provided on each end with the respectiveend's annular groove provided between the lateral sides. The lateralsides provide annular tapers that extend radially inward away from therespective end's annular groove. The tube provides a cavity that has anopening at each of the ends and an orifice is provided in the tube influid communication with the cavity.

In a further embodiment of any of the above, a seal is arranged in eachof the annular grooves.

In a further embodiment of any of the above, multiple orifices areprovided about a circumference of the neck.

In a further embodiment of any of the above, a gas turbine engineincludes a fan section. A turbine section is coupled to the fan sectionvia a geared architecture. The geared architecture includes the geartrain. The first member is a torque frame, and the second member is aflex support.

In a further embodiment of any of the above, the gas turbine engineincludes a sun gear. Star gears are supported by the carrier and a ringgear circumscribes the star gears. The star gears intermesh with the sungear and the ring gear.

In a further embodiment of any of the above, the fan section includes afan coupled to the ring gear and the turbine section includes a highpressure turbine section and a low pressure turbine section. A low speedspool supports the low pressure turbine section and is coupled to thesun gear. The torque frame is grounded to a static structure.

In a further embodiment of any of the above, the flex support has abellow. The flex support is grounded to a static structure and multipleviscous dampers are arranged circumferentially between the torque frameand the flex support.

In a further embodiment of any of the above, the torque frame and theflex support respectively include first and second apertures alignedwith one another in an axial direction. The viscous damper extendsbetween and is received in the first and second apertures. The viscousdamper is provided by a tube having opposing ends each supporting aseal. Each seal engages a respective first and second apertures. Thetube provides a cavity and an orifice is provided in the tube in fluidcommunication with the cavity. The cavity provides a viscous dampingchamber between the torque frame and the flex support.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure can be further understood by reference to the followingdetailed description when considered in connection with the accompanyingdrawings wherein:

FIG. 1 schematically illustrates a gas turbine engine embodiment.

FIG. 2 is a schematic view of an epicyclic gear train embodiment for afan drive gear system.

FIG. 3 is a partial cross-sectional schematic view of a fan drive gearsystem embodiment.

FIG. 4 is an enlarged view of a portion of the fan drive gear systemshown in FIG. 2.

FIG. 5 is a perspective view of a damper embodiment shown in FIG. 4.

DETAILED DESCRIPTION

FIG. 1 schematically illustrates a gas turbine engine 20. The gasturbine engine 20 is disclosed herein as a two-spool turbofan thatgenerally incorporates a fan section 22, a compressor section 24, acombustor section 26 and a turbine section 28. Alternative engines mightinclude an augmentor section (not shown) among other systems orfeatures. The fan section 22 drives air along a bypass flowpath B whilethe compressor section 24 drives air along a core flowpath C forcompression and communication into the combustor section 26 thenexpansion through the turbine section 28. Although depicted as aturbofan gas turbine engine in the disclosed non-limiting embodiment, itshould be understood that the concepts described herein are not limitedto use with turbofans as the teachings may be applied to other types ofturbine engines including three-spool architectures.

The engine 20 generally includes a low speed spool 30 and a high speedspool 32 mounted for rotation about an engine central longitudinal axisA relative to an engine static structure 36 via several bearing systems38. It should be understood that various bearing systems 38 at variouslocations may alternatively or additionally be provided.

The low speed spool 30 generally includes an inner shaft 40 thatinterconnects a fan 42, a low pressure (or first) compressor section 44and a low pressure (or first) turbine section 46. The inner shaft 40 isconnected to the fan 42 through a geared architecture 48 to drive thefan 42 at a lower speed than the low speed spool 30. The high speedspool 32 includes an outer shaft 50 that interconnects a high pressure(or second) compressor section 52 and high pressure (or second) turbinesection 54. A combustor 56 is arranged between the high pressurecompressor 52 and the high pressure turbine 54. A mid-turbine frame 57of the engine static structure 36 is arranged generally between the highpressure turbine 54 and the low pressure turbine 46. The mid-turbineframe 57 supports one or more bearing systems 38 in the turbine section28. The inner shaft 40 and the outer shaft 50 are concentric and rotatevia bearing systems 38 about the engine central longitudinal axis A,which is collinear with their longitudinal axes. As used herein, a “highpressure” compressor or turbine experiences a higher pressure than acorresponding “low pressure” compressor or turbine.

The core airflow C is compressed by the low pressure compressor 44 thenthe high pressure compressor 52, mixed and burned with fuel in thecombustor 56, then expanded over the high pressure turbine 54 and lowpressure turbine 46. The mid-turbine frame 57 includes airfoils 59 whichare in the core airflow path. The turbines 46, 54 rotationally drive therespective low speed spool 30 and high speed spool 32 in response to theexpansion.

The engine 20 in one example is a high-bypass geared aircraft engine. Ina further example, the engine 20 bypass ratio is greater than about six(6), with an example embodiment being greater than ten (10), the gearedarchitecture 48 is an epicyclic gear train, such as a star gear systemor other gear system, with a gear reduction ratio of greater than about2.3 and the low pressure turbine 46 has a pressure ratio that is greaterthan about 5. In one disclosed embodiment, the engine 20 bypass ratio isgreater than about ten (10:1), the fan diameter is significantly largerthan that of the low pressure compressor 44, and the low pressureturbine 46 has a pressure ratio that is greater than about 5:1. Lowpressure turbine 46 pressure ratio is pressure measured prior to inletof low pressure turbine 46 as related to the pressure at the outlet ofthe low pressure turbine 46 prior to an exhaust nozzle. It should beunderstood, however, that the above parameters are only exemplary of oneembodiment of a geared architecture engine and that the presentinvention is applicable to other gas turbine engines including directdrive turbofans.

A significant amount of thrust is provided by the bypass flow B due tothe high bypass ratio. The fan section 22 of the engine 20 is designedfor a particular flight condition—typically cruise at about 0.8 Mach andabout 35,000 feet. The flight condition of 0.8 Mach and 35,000 ft, withthe engine at its best fuel consumption—also known as “bucket cruiseThrust Specific Fuel Consumption (‘TSFC’)”—is the industry standardparameter of 1 bm of fuel being burned per hour divided by 1 bf ofthrust the engine produces at that minimum point. “Fan pressure ratio”is the pressure ratio across the fan blade alone, without a Fan ExitGuide Vane (“FEGV”) system. The low fan pressure ratio as disclosedherein according to one non-limiting embodiment is less than about 1.45.“Low corrected fan tip speed” is the actual fan tip speed in ft/secdivided by an industry standard temperature correction of [(Tambient degR)/518.7)̂0.5]. The “Low corrected fan tip speed” as disclosed hereinaccording to one non-limiting embodiment is less than about 1150ft/second.

An example geared architecture 48 is schematically shown in a gearcompartment 96 in FIGS. 2 and 3. The geared architecture 48 includes asun gear 60, which is coupled to the inner shaft 40, as illustrated inFIG. 3. Star gears 62 are arranged circumferentially about the sun gear60 and intermesh with the sun gear 60 and a ring gear 64, whichcircumscribes the star gear 62. In one example, the ring gear 64 iscoupled to the fan 42. It should be understood that the gearedarchitecture 48 illustrated in FIGS. 2 and 3 is exemplary only and canbe configured other than illustrated.

A carrier 66 supports the star gears 62 relative to the sun gear 60 andring gear 64. A torque frame 68 is connected to the carrier 66 by pins70. The torque frame 68 is secured to the static structure 36 by a flexsupport 72, which has a bellow for permitting slight movement of thegeared architecture 48 relative to the static structure 36. In theexample, fasteners 73 secure the torque frame 68 and the flex support72, which are metallic in one example, to one another to facilitateassembly and disassembly of the geared architecture 48. However, thetorque frame 68 and flex support 72 are also spaced apart from oneanother in an axial direction at a location radially outward from thefasteners 73.

Referring to FIGS. 3 and 4, the torque frame 68 and flex support 72respectively include first and second apertures 74, 76 that are alignedwith one another in the axial direction. A damper 78, which is metallicin one example, is provided between the torque frame 68 and flex support72 and received within the first and second apertures 74, 76, the gearedarchitecture 48, provide desired stiffness and/or avoid naturalfrequencies. In one example, multiple dampers are arrangedcircumferentially between the torque frame 68 and flex support 72, asillustrated in FIG. 2. It should be understood that the dampers 78 maybe configured in any desirable configuration and more or fewer dampers78 may be used than illustrated.

Referring to FIGS. 4 and 5, the damper 78 is provided by a tube 79includes opposing ends 80 with a neck 82 arranged between the ends 80.The neck 82 has a diameter that is smaller than a diameter of the ends80. Each end 80 includes an annular groove 84 that receives a seal 92.Lateral sides 86 are provided on each end 80 with the annular groove 84arranged between the lateral sides 86. The lateral sides 86 provide anannular taper that extends radially inward from the annular groove 84.The smaller diameter neck 82 and the tapered lateral sides 86 enablesthe damper 78 to articulate within the first and second apertures 74, 76about the seals 92 during vibrations without permitting metal-to-metalcontact between the damper 78 and the torque frame 68 or the flexsupport 72.

The damper 78 includes a cavity 88 that extends along its axial lengthbetween openings 90 provided at each end 80. The cavity 88 provides aviscous damping chamber. One or more orifices 94 are provided in theneck 82, for example, and are in fluid communication with the cavity 88.The orifices 94 permit an oil-mist in the gear compartment 96 to enterthe cavity 88. Any oil collecting in the cavity 88 may drain through theorifices 94. The volume of the cavity 88 and the size, number andconfiguration of the orifices 94 are configured to damp a vibrationalinput from the geared architecture 48.

Although an example embodiment has been disclosed, a worker of ordinaryskill in this art would recognize that certain modifications would comewithin the scope of the claims. For that reason, the following claimsshould be studied to determine their true scope and content.

1. A gas turbine engine comprising: first and second members spaced apart from one another at a location; a gear train supported by the first member; and a damper provided between the first member and the second member at the location.
 2. The gas turbine engine according to claim 1, wherein the first member is a torque frame, and the second member is a flex support having a bellow, the flex support grounded to a static structure.
 3. The gas turbine engine according to claim 2, wherein the torque frame and flex support are secured to one another by fasteners in an area spaced radially inward from the location.
 4. The gas turbine engine according to claim 3, wherein multiple viscous dampers are arranged circumferentially between the torque frame and the flex support, and the bellow is provided between the fasteners and the viscous dampers.
 5. The gas turbine engine according to claim 4, wherein the torque frame supports a carrier to which star gears are mounted, a sun gear is arranged centrally relative to and intermeshing with the star gears, and a ring gear circumscribing and intermeshing with the star gears.
 6. The gas turbine engine according to claim 5, comprising a fan coupled to the ring gear, and a low speed spool coupled to the sun gear.
 7. The gas turbine engine according to claim 2, wherein the first and second members respectively include first and second apertures aligned with one another in an axial direction, and wherein the damper is a viscous damper extending between and received in the first and second apertures.
 8. The gas turbine engine according to claim 7, wherein the viscous damper is a tube having opposing ends each supporting a seal, each seal engaging a respective first and second aperture.
 9. The gas turbine engine according to claim 8, wherein the tube provides a cavity, and an orifice is provided in the tube in fluid communication with the cavity, the cavity providing a viscous damping chamber between the first and second members.
 10. The gas turbine engine according to claim 9, wherein at least one of the gear train and the second member is configured to produce a vibrational input, and the orifice and viscous damping chamber is configured to damp the vibrational input.
 11. The gas turbine engine according to claim 10, wherein each end includes an annular groove receiving a respective seal, and lateral sides are provided on each end with the respective end's annular groove provided between the lateral sides, the lateral sides providing annular tapers extending radially inward away from the respective end's annular groove and configured to permit articulation of the viscous damper relative to the first and second members.
 12. The gas turbine engine according to claim 11, wherein the tube includes a neck arranged between ends and having a diameter that is smaller than a diameter of the ends.
 13. The gas turbine engine according to claim 1, wherein the damper includes a tube having opposing ends each with an annular groove, a neck arranged between ends and having a diameter that is smaller than a diameter of the ends, lateral sides provided on each end with the respective end's annular groove provided between the lateral sides, the lateral sides providing annular tapers extending radially inward away from the respective end's annular groove, the tube provides a cavity having an opening at each of the ends, and an orifice is provided in the tube in fluid communication with the cavity.
 14. The gas turbine engine according to claim 13, comprising a seal arranged in each of the annular grooves.
 15. The gas turbine engine according to claim 14, wherein multiple orifices are provided about a circumference of the neck.
 16. The gas turbine engine according to claim 1, comprising: a fan section; and a turbine section coupled to the fan section via a geared architecture, the geared architecture includes the gear train, and the first member is a torque frame, and the second member is a flex support spaced.
 17. The gas turbine engine according to claim 16, comprising a sun gear, star gears supported by the carrier, and a ring gear circumscribing the star gears, the star gears intermeshing with the sun gear and the ring gear.
 18. The gas turbine engine according to claim 17, wherein the fan section includes a fan coupled to the ring gear, and the turbine section includes a high pressure turbine section and a low pressure turbine section, and a low speed spool supporting the low pressure turbine section and coupled to the sun gear, the torque frame grounded to a static structure.
 19. The gas turbine engine according to claim 18, wherein the flex support has a bellow, the flex support grounded to a static structure, and multiple viscous dampers are arranged circumferentially between the torque frame and the flex support.
 20. The gas turbine engine according to claim 19, wherein the torque frame and the flex support respectively include first and second apertures aligned with one another in an axial direction, the viscous damper extends between and is received in the first and second apertures, the viscous damper provided by a tube having opposing ends each supporting a seal, each seal engaging a respective first and second apertures, the tube provides a cavity, and an orifice is provided in the tube in fluid communication with the cavity, the cavity providing a viscous damping chamber between the torque frame and the flex support. 